This proposal has the following objectives: 1. To develop an innovative method of postmarket drug monitoring in a non-hospitalized population. The method is based upon a patient-initiated reporting system via telephone to a central monitoring station. Patient cooperation is elicited via an "insert" enclosed in the pharmacy sack along with the patient's medication. 2. To examine the relative sensitivity and specificity of the new method in detecting adverse clinical events occurring after starting treatment with tricyclic antidepressants. Accuracy in terms of under- or over-reporting is assessed by comparing incidence estimates obtained from the sample receiving the insert with incidence estimates from an independent control sample of randomly assigned "no-insert" patients who receive systematic individual interviews. 3. To determine--by utilizing appropriate experimental controls and statistical analyses--whether strong supportive evidence (although not conclusive proof) can be adduced to show that specific adverse clinical events detected by the new method can be attributed to tricyclic antidepressants. The "experimental controls" here refer to the inclusion of selected antibiotics as a different class of drug having a known side-effect profile greatly disparate from that of the tricyclics. A total of 4,200 patients filling a prescription for one of these drugs in the University of Texas Medical Branch outpatient pharmacies will be entered into the study.